Papers by osman sivrikaya
Artıbilim: Adana Alparslan Türkeş Bilim ve Teknoloji Üniversitesi Fen Bilimleri Dergisi, Jun 30, 2021
Some factors affect the coal grindability such as moisture content, petrographic composition, har... more Some factors affect the coal grindability such as moisture content, petrographic composition, hardness, fragility and rank of the coals. The grindability of the pre-heated coal is assumed to be positively affected and facilitates size reduction processes. In this study, effects and relationship of traditional drying methods (air circulated fan oven and air drying) and microwave drying on the grindability of coals were investigated. For this purpose, two different lignite coals; Tufanbeyli and Ilgın lignite coals were selected. The research parameters; drying method, drying temperature, drying time were selected as independent variables. The particle size distributions of ground coal samples in a rod mill, under the same conditions were determined. The particle size distribution, d50 and d80 values of the ground coals were considered as dependent variables. As a result of the experimental studies, it was found that the finest coal particle size distribution was determined to be Tufanbeyli lignite, which was dried at 105 o C for 240 minutes. The d50 and d80 values were 95 µm and 130 µm and Ilgın coal was reached at the microwavedried coal at 800 W for 20 minutes, while the d50 and d80 values were 100 µm and 205 µm, respectively.
Particulate Science and Technology
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2015
Spontaneous combustion occurs in stockpiles in coal managements and causes interruptions in produ... more Spontaneous combustion occurs in stockpiles in coal managements and causes interruptions in production and economical and environmental problems. This work was performed on an industrial-scale stockpile formed with +18-mm clean coal. The temperature changes of the stockpile exposed to sun’s rays were measured. Concurrently, the values of solar intensity, air temperature, air pressure, air humidity, wind speed, and wind direction affecting the stockpile were measured continuously. A statistical model to predict spontaneous combustion was developed by multi-nonlinear-regression analyses. The correlation coefficients were calculated around 0.95 levels. With this model, the effects of atmospheric conditions on spontaneous combustion of coal stockpiles can be predicted.
The tumbling-abrasion indices of iron ore pellets are measured according to instructions in ASTM ... more The tumbling-abrasion indices of iron ore pellets are measured according to instructions in ASTM E279- 97 (2010). This test measures the resistance of the product pellets under certain abrasive condition in a standard test drum. However, this test requires 11.3 kg pellet to carry out a single tumbling-abrasion test. This amount of pellet can be obtained from industrial-scale pellet production. However, it is impossible to produce this amount of pellet in laboratory-scale investigation since the capacities of laboratory equipment are low. Therefore, this test can not be applied in laboratory-scale pellet investigations. In this study, laboratory studies were carried out to determine the tumbling-abrasion indices of pellets in small quantities (500-1000 gram) via an alternative test method. Industrial-scaleproduced 4 different pellet samples were obtained from a company. Tumbling-abrasion tests were carried out with a scale-down test drum under different test conditions. It has been i...
Ömer Halisdemir Üniversitesi Mühendislik Bilimleri Dergisi, 2019
Petrolün tektonik hareketler sonucu kendi yatağından ayrılarak çevredeki yarık ve çatlaklara yerl... more Petrolün tektonik hareketler sonucu kendi yatağından ayrılarak çevredeki yarık ve çatlaklara yerleşerek sıcaklık ve basıncın etkisi ile metamorfizmaya uğramış maddelere asfaltit denir. Petrol kökenli olması, kalorisinin yüksek olması ve içerisinde nikel, molibden, vanadyum gibi elementleri bulundurması nedeniyle önemli bir kaynak olarak görülmektedir. Türkiye'de Şırnak ve Hakkari illerinde 13 filon halinde bulunan asfaltit yatakları tespit edilmiştir. Kalori değerinin yüksek olması Şırnak-Silopi'de bulunan asfaltit kaynağının, 405 MW gücünde akışkan yataklı kazan teknolojili termik santral kurulmasına olanak sağlamıştır. Mineral madde ve kükürt asfaltitin yakıt olarak kullanılmasında büyük bir sorundur. Bu yüzden yerleşim merkezlerinde evsel ısıtmalarda kullanılması sakıncalıdır. Asfaltitleri çevreye uyumlu bir enerji kaynağı haline getirmek için çeşitli temizleme çalışmaları yapılmıştır. Yapılan çalışmalar sonucunda kül oranında düşüş saptanmasına rağmen kükürt değerlerinde istenilen oranda düşüş gözlemlenememiştir. Bu çalışmada asfaltit hakkında bilgiler Türkiye'nin asfaltit kaynakları ile birlikte verilirken asfaltitin enerji kaynağı olarak kullanımından kaynaklanan çevresel zararlarını azaltmak için yapılan çalışmalar hakkında kapsamlı bilgiler sunulmuştur.
Coal washery rejected coals and coal slurries have better options in froth flotation as a separat... more Coal washery rejected coals and coal slurries have better options in froth flotation as a separation process. In this study, coal slurry received from Sudamdih coal washery, Jharkhand, India, examined for cleaning through fixed cell flotation. The Petrography study of the feed sample showed the presence of vitrinite, semi vitrinite and liptinite and inertinite as major minerals. General full factorial statistical design package (Minitab V17) was used to develop the regression models for the responses like froth height, froth density, recovery and ash content of clean coal. Results showed that experimental responses like froth height, froth density, recovery and ash content were found to be more sensitive to the frother dosage. The coefficient of correlation (R2) values between the experimental and the predicted values of the flotation responses was found to be >0.98 for all the models. Further, flotation tests were conducted for varying pulp density and its effect on recovery, fr...
TURKISH JOURNAL OF ELECTRICAL ENGINEERING & COMPUTER SCIENCES, 2018
Ironmaking & Steelmaking, 2017
ABSTRACT Limestone and dolostone are used in industries depending on their physicochemical charac... more ABSTRACT Limestone and dolostone are used in industries depending on their physicochemical characteristics. They can be used in construction, agricultural, environmental industries and especially in ironmaking and steelmaking as flux. Dolomite is also used in the production of refractory materials. As the properties of products are significantly affected by physicochemical specifications of limestone or dolomite, the characterisation of those materials is important. This study was initiated to analyse the chemical, decrepitation, and degradation properties of dolomite and limestone samples to determine their suitability as flux. Since the degradation indices were found different for the chemically similar samples, the study was expanded to determine the reason. Complete physicochemical and thermal characterisation was performed via XRF, XRD, TG, FTIR, and thin section microscopic analyses. Although two dolomite samples were mineralogically similar, thermal behaviours were determined different. Microscopic analyses results showed that the crystal structures/sizes affect the thermal behaviour and degradation index of carbonate samples.
International Journal of Coal Preparation and Utilization, 2016
ABSTRACT The use of low-rank coals as an energy source may cause environmental problems. Washabil... more ABSTRACT The use of low-rank coals as an energy source may cause environmental problems. Washability of a Turkish lignite sample was evaluated by conventional methods with sink-and-float tests and a Reichert spiral. Also, the fine size fractions were cleaned with enhanced gravity separation techniques, a multigravity separator (MGS), and a Falcon concentrator. The as-received lignite sample was sieved into five size fractions (-100 +25.4 mm; -25.4 +12.7 mm; -12.7 +1.2 mm; -1.2 +0.15 mm; -0.15 mm) and the washability characteristics of the first three fractions were separately investigated with sink-float tests. The -1.2 +0.15 mm size fraction was cleaned using a Reichert spiral. Tests with the MGS and the Falcon concentrator were conducted with a -0.15 mm fine size fraction. Sink-float tests results showed that the tested coal can be classified as difficult-to-clean coal due to the presence of high near-gravity material at lower separation densities than 1.7 g/cm3. However, the production of cleaner coal was easier at finer size fractions due to further liberation. Enhanced gravity separation techniques presented better results in terms of combustible recoveries.
Mineral Processing and Extractive Metallurgy Review, 2013
Iron ore pellets must have sufficient mechanical strengths against degradation in all stages of p... more Iron ore pellets must have sufficient mechanical strengths against degradation in all stages of pellet production. Low strength is also a problem for product pellets since they abrade during transportation to the reduction furnaces. The use of a binder is necessary to provide sufficient strength to the pellets and for better operation and handling of pellets. Bentonite is the standard binder in the industry; however, it is considered an impurity due to its acid oxide contents. Organic binders have been tested for many years as alternative binder to bentonite. They have been found to give sufficient wet pellet properties. However, they failed to provide sufficient strength to the preheated and fired pellets due to lack of slag bonding. It has been assumed that one possible effective method to improve the preheated and fired pellet strengths is addition of a slag-bonding constituent. In this study, calcined colemanite was added to the pellet feed to overcome the lower strength problem encountered with organic binder use. The strength of pellets produced with organic binders and calcined colemanite alone and in combination was comparatively studied against the strength of pellets made with standard bentonite binder in magnetite concentrate pelletizing. The results showed that addition of calcined colemanite into the pellet mixture improved the preheated and fired pellet strengths of pellets produced with organic binders.
Ironmaking & Steelmaking, 2013
Fuel, 2014
h i g h l i g h t s The cleaning potential of a low-rank lignitic coal has been characterized. De... more h i g h l i g h t s The cleaning potential of a low-rank lignitic coal has been characterized. Dense medium, gravity-based and flotation techniques were applied. Coal was found difficult-to-clean due to its high content of near-gravity material. Clean coal with sufficient calorific value and ash content can be used in industry. Low calorific value middling and rejected coal can be used in thermal power plant.
The Open Mineral Processing Journal, 2010
I hereby declare that all information in this document has been obtained and presented in accorda... more I hereby declare that all information in this document has been obtained and presented in accordance with academic rules and ethical conduct. I also declare that, as required by these rules and conduct, I have fully cited and referenced all material and results that are not original to this work.
Science of Sintering
The present study aims to investigate the use of mixed hematite and magnetite ores in iron ore pe... more The present study aims to investigate the use of mixed hematite and magnetite ores in iron ore pellet production. Pelletizing tests were carried out on the hematite and magnetite premixed pellet feed. Drop number and compressive strength tests for green and dry pellets; porosity, compressive strength and reducibility tests for fired pellets were carried out to determine the influence of mixing ratios of both iron oxides on those pellet properties. Experimental results showed that as the hematite content in the mix pellets is increased, the green drop number decreased from 6.5 to 5.2, the green compressive strength decreased from 1.51 to 1.28 kg/pellet and the dry compressive strength decreased from 2.50 to 1.60 kg/pellet. It was determined that fired compressive strength of mix pellets decreased from 380 to 230 kg/pellet when the hematite content in the mixed pellet is increased. The reducibility of mix pellets had almost the same trend and it was faster up to 40 min reduction time....
This study was started to find alternative binders to bentonite and to recover the low preheated ... more This study was started to find alternative binders to bentonite and to recover the low preheated and fired pellet mechanical strengths of organic binders-bonded pellets. Bentonite is considered as a chemical impurity for pellet chemistry due to acid constituents (SiO2 and Al2O3). Especially addition of silica-alumina bearing binders is detrimental for iron ore concentrate with high acidic content. Organic binders are the most studied binders since they are free in silica. Although they yield pellets with good wet strength; they have found limited application in industry since they fail to give sufficient physical and mechanical strength to preheated and fired pellets. It is investigated that how insufficient preheated and fired pellet strengths can be improved when organic
European Journal of Science and Technology
Öz Bu çalışmada yıkanmış Türk linyit kömürlerinin üst ısıl değeri (GCV), makine öğrenmesi yönteml... more Öz Bu çalışmada yıkanmış Türk linyit kömürlerinin üst ısıl değeri (GCV), makine öğrenmesi yöntemleri ile kömür numunelerinin kuru baz kısa analiz sonuçları kullanılarak tahmin edilmiştir. Laboratuvar kömür analiz sonuçlarından elde edilen kül (A), uçucu madde (VM), kükürt (S) ve GCV değişkenleri kullanılarak veri kümesi oluşturulmuştur. Veri kümesine, Destek Vektör Regresyonu (SVR) ile Çok Katmanlı Algılayıcı (MLP), Genel Regresyon Sinir Ağı (GRNN) ve Radyal Temelli Fonksiyon Sinir Ağı (RBFN) olmak üzere üç farklı Yapay Sinir Ağı (ANN) uygulanarak GCV tahmin modelleri geliştirilmiştir. Geliştirilen modellerin performans genelleştirme kabiliyeti 10-katlı çapraz-doğrulama kullanılarak sağlanmış ve modellerin tahmin doğruluğu, performans ölçütleri Çoklu Korelasyon Katsayısı (R), Kök Ortalama Kare Hatası (RMSE), Ortalama Mutlak Hata (MAE) ve Ortalama Mutlak Yüzde Hata (MAPE) kullanılarak hesaplanmıştır. Sonuçlar, GCV tahmini için, tüm modeller arasında SVR tabanlı modelin ANN tabanlı modellere göre biraz daha iyi, ANN tabanlı modeller arasında ise RBFN tabanlı modelin MLP ve GRNN tabanlı modellere göre daha iyi performans gösterdiğini ortaya koymuştur.
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Papers by osman sivrikaya